Species distribution and antimicrobial susceptibility profiles of nontuberculous mycobacteria, with an exploratory 12-month completer outcome analysis: a single-center retrospective study from Shandong Province, China
5 affiliations
- 1Department of Critical Care Medicine, Shandong Provincial Maternal and Child Health Care Hospital Affiliated to Qingdao University, Jinan
- 2Department of Tuberculosis Medicine, Public Health Clinical Center Affiliated to Shandong University, Jinan
- 3Department of Breast and Thyroid Surgery, Shandong Provincial Maternal and Child Health Care Hospital Affiliated to Qingdao University, Jinan
- 4Department of Respiratory Endoscopy, Public Health Clinical Center Affiliated to Shandong University, Jinan
- 5Department of Respiratory and Critical Care Medicine, Public Health Clinical Center Affiliated to Shandong University, Jinan
Abstract
The incidence of nontuberculous mycobacterial pulmonary disease (NTM-PD) is rising worldwide, yet clinical breakpoints validated against treatment outcome exist for very few antimycobacterial agents. We characterized species distribution and broth-microdilution minimum inhibitory concentration (MIC) profiles in 606 consecutive isolates, one per patient, collected between February 2021 and October 2024 at a provincial referral hospital in Shandong Province, China. Outcomes were examined in the 127 patients (21.0% of all 606) who received at least 12 months of therapy. Testing followed CLSI M24 (3rd edition). The panel reports MIC values only and the laboratory assigns categories, having revised its breakpoints twice as successive CLSI standards were adopted. To apply one criterion throughout, the four agents with CLSI clinical breakpoints for the Mycobacterium avium complex (MAC), namely clarithromycin, amikacin, linezolid and moxifloxacin, were reclassified from individual MIC values. MAC accounted for 73.1% of isolates, the Mycobacterium abscessus complex (MABC) for 12.4% and Mycobacterium kansasii for 8.1%. Against MAC, 98.9% of isolates were susceptible to clarithromycin, 99.8% to amikacin, 99.3% to linezolid and 96.2% to moxifloxacin. Azithromycin was assigned to a higher category than clarithromycin in 97 isolates, and 93 of these remained in the lowest clarithromycin category; this difference reflects the thresholds applied to the two macrolides rather than independent resistance. Ethambutol MICs were concentrated at the upper end of the tested range (44.6% at the highest concentration), which describes the MIC distribution rather than resistance, because no clinical breakpoint exists for ethambutol against MAC. Yearly distributions showed no monotonic trend ( P = 0.063). Cure was achieved in 58.8% of MAC-PD, 54.5% of MABC-PD and 95.0% of Mycobacterium kansasii -PD patients; these estimates describe the completer cohort only. Cavitary disease was associated with substantially lower odds of cure (adjusted odds ratio 0.15, 95% CI 0.04–0.54, P = 0.004), whereas regimen composition was not. Susceptibility testing is actionable for the macrolides and amikacin, with clarithromycin the appropriate macrolide class representative; for other agents the categories depend on locally defined criteria that changed during the study. NTM surveillance should therefore be built on MIC values, and should record the interpretive criteria applied.
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BibTeX
@article{zhang2026species,
title = {{Species distribution and antimicrobial susceptibility profiles of nontuberculous mycobacteria, with an exploratory 12-month completer outcome analysis: a single-center retrospective study from Shandong Province, China}},
author = {Jie Zhang and Xiao Ru and Yuming Shao and Li Xu and Hengjian Fan},
journal = {Frontiers in Microbiology},
year = {2026},
month = oct,
doi = {10.3389/fmicb.2026.1917292},
url = {https://www.frontiersin.org/articles/10.3389/fmicb.2026.1917292/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Species distribution and antimicrobial susceptibility profiles of nontuberculous mycobacteria, with an exploratory 12-month completer outcome analysis: a single-center retrospective study from Shandong Province, China
AU - Jie Zhang
AU - Xiao Ru
AU - Yuming Shao
AU - Li Xu
AU - Hengjian Fan
PY - 2026
DA - 2026/10/20
JO - Frontiers in Microbiology
DO - 10.3389/fmicb.2026.1917292
UR - https://www.frontiersin.org/articles/10.3389/fmicb.2026.1917292/full
AB - The incidence of nontuberculous mycobacterial pulmonary disease (NTM-PD) is rising worldwide, yet clinical breakpoints validated against treatment outcome exist for very few antimycobacterial agents. We characterized species distribution and broth-microdilution minimum inhibitory concentration (MIC) profiles in 606 consecutive isolates, one per patient, collected between February 2021 and October 2024 at a provincial referral hospital in Shandong Province, China. Outcomes were examined in the 127 patients (21.0% of all 606) who received at least 12 months of therapy. Testing followed CLSI M24 (3rd edition). The panel reports MIC values only and the laboratory assigns categories, having revised its breakpoints twice as successive CLSI standards were adopted. To apply one criterion throughout, the four agents with CLSI clinical breakpoints for the Mycobacterium avium complex (MAC), namely clarithromycin, amikacin, linezolid and moxifloxacin, were reclassified from individual MIC values. MAC accounted for 73.1% of isolates, the Mycobacterium abscessus complex (MABC) for 12.4% and Mycobacterium kansasii for 8.1%. Against MAC, 98.9% of isolates were susceptible to clarithromycin, 99.8% to amikacin, 99.3% to linezolid and 96.2% to moxifloxacin. Azithromycin was assigned to a higher category than clarithromycin in 97 isolates, and 93 of these remained in the lowest clarithromycin category; this difference reflects the thresholds applied to the two macrolides rather than independent resistance. Ethambutol MICs were concentrated at the upper end of the tested range (44.6% at the highest concentration), which describes the MIC distribution rather than resistance, because no clinical breakpoint exists for ethambutol against MAC. Yearly distributions showed no monotonic trend ( P = 0.063). Cure was achieved in 58.8% of MAC-PD, 54.5% of MABC-PD and 95.0% of Mycobacterium kansasii -PD patients; these estimates describe the completer cohort only. Cavitary disease was associated with substantially lower odds of cure (adjusted odds ratio 0.15, 95% CI 0.04–0.54, P = 0.004), whereas regimen composition was not. Susceptibility testing is actionable for the macrolides and amikacin, with clarithromycin the appropriate macrolide class representative; for other agents the categories depend on locally defined criteria that changed during the study. NTM surveillance should therefore be built on MIC values, and should record the interpretive criteria applied.
SN - 1664-302X
ER -